[Qemu-devel] [PATCH] Re: RTC polling mode broken

[Bernhard Kauer <kauer@os.inf.tu-dresden.de>]

On Thu, Aug 27, 2009 at 03:33:30PM +0300, Gleb Natapov wrote:
> On Thu, Aug 27, 2009 at 01:18:03PM +0200, Bernhard Kauer wrote:
> > Suppose I have some software that does not run with Qemu 
> > and I have done the following steps:
> > 
> > 	1. found that it is bug in Qemu and not in my software
> > 	2. produced a patch that fixed the problem for my test-case
> > 	3. send the patch with an explanation to the mailinglist
> > 	4. waited 6 weeks for comments or inclusion in Qemu
> > 
> > Now what should I do, to get the bug fixed?
> > 
> Resend the patch? (no need to what for 6 week to do that BTW)

How often?


	Bernhard



> > On Wed, Jul 15, 2009 at 12:50:43PM +0200, Bernhard Kauer wrote:
> > > The RTC emulation does not set the IRQ flags independent of the IRQ enable bits.
> > > 
> > > The original MC146818A datasheet from 1984 notes:
> > > 	"flag bits in Register C [...] are set independent of the
> > > 	state of the corresponding enable bits in Register B"
> > > Similar sections can be found in newer documentation e.g. in rtc82885.
> > > 
> > > Qemu and Bochs set the IRQ flags only if they are enabled,
> > > which breaks drivers polling on them.
> > > 
> > > The following patch corrects this for the update-ended-flag in Qemu only.
> > > It currently does not fix the handling of the other flags.
> > > 
> > > 
> > > Signed-off-by: Bernhard Kauer <kauer@tudos.org>
> > > 
> > > 
> > > diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
> > > index 2022548..2b040a7 100644
> > > --- a/hw/mc146818rtc.c
> > > +++ b/hw/mc146818rtc.c
> > > @@ -421,9 +421,10 @@ static void rtc_update_second2(void *opaque)
> > >      }
> > >  
> > >      /* update ended interrupt */
> > > +    s->cmos_data[RTC_REG_C] |= REG_C_UF;
> > >      if (s->cmos_data[RTC_REG_B] & REG_B_UIE) {
> > > -        s->cmos_data[RTC_REG_C] |= 0x90;
> > > -        rtc_irq_raise(s->irq);
> > > +      s->cmos_data[RTC_REG_C] |= REG_C_IRQF;
> > > +      rtc_irq_raise(s->irq);
> > >      }
> > >  
> > >      /* clear update in progress bit */
> >